Levitation: Is it Real?

One hundred years ago, in 1911, a Dutchman by the name of Heike
Kamerlingh Onnes discovered superconductivity. He found that mercury
had no electrical resistance when cooled to 4.15 kelvins, or -451.93
degrees Fahrenheit. (Dry ice has a surface temperature of -109.3 ºF.
Handling dry ice with your bare hand will give you frostbite!)

Today, the race is on to find materials that are superconducting
at room temperature. Once this happens, the world-wide web of
electronics, power and transportation will be revolutionized.

NSLS supports a rich program of research to understand the basic
phenomenon of superconductivity and develop it in ways that will
facilitate commercialization.

Often, the work zigzags in unexpected ways. Over a decade ago,
scientists using NSLS discovered a low-energy kink in the energy
bands of electrons in high-temperature superconductors just as they
go through the transition temperature from their normal to
superconducting state. Because this kink is a signature for the
mechanism that causes superconductivity in low-temperature
superconductors, they had hoped that a similar kink in
high-temperature superconductors would show the same mechanism at
work.

More recent work, however, unveiled a second and much larger kink
in the high-temperature superconductors “LBCO” (scientific shorthand
for the elements it contains: lanthanum, barium, copper, and oxygen)
and “BSCCO” (containing bismuth, strontium, calcium, copper, and
oxygen).

And here’s another wrinkle. Scientists have found similar energy
scales and gaps in a material that is not a superconductor. The
material is a special form of LBCO, where there is exactly one
barium atom for every eight copper atoms. With less or more barium,
the material acts as a high-temperature superconductor (this was
actually the very first high-temperature superconductor discovered).
But at the one-to-eight ratio, the material momentarily loses its
superconductivity.

So the mystery continues.

But wait! What does this have to do with levitation?

In 1933, 23 years after the Dutchman Onnes discovered
superconductivity, the Germans Walther Meissner and Robert
Ochsenfeld found that a superconducting material will repel a
magnetic field. The effect is so strong that a magnet can actually
be levitated over a superconductor.

Maglev trains exploit this property by levitating the cars above
the track, eliminating the friction that slows down all forms of
land transportation.

JR Tokai, a private railroad company in Japan, is developing
plans for a superconducting maglev route between Tokyo and Nagoya.
Using a large electrical power source, metal coils lining a track,
and large magnets attached to the underside of the cars, these
trains would run at 310 miles per hour.

So levitation is real. In fact, magnetic levitation with
superconducting magnets was invented and patented by two Brookhaven
scientists, James Powell and Gordon Danby. An engineer, Powell came
up with the idea while stuck in a traffic jam on the Throgs Neck
Bridge, which spans the East River between the Bronx and Queens,
boroughs of New York City. He developed the idea with Danby, a
physicist, and they were awarded a U.S. patent in 1968. Various
demonstration systems have been built through the years.

Research on superconductors at NSLS is funded by the U.S.
Department of Energy, which is has a keen interest in understanding
the mechanisms of superconducting materials - particularly those
that can carry current with zero resistance at higher temperatures -
because these materials have many potential applications in
improving the efficiency of energy generation and transmission.

One of ten national laboratories overseen and primarily funded by the Office of Science of the
U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical,
biomedical, and environmental sciences, as well as in energy technologies and national security.
Brookhaven Lab also builds and operates major scientific facilities available to university, industry
and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven
Science Associates, a limited-liability company founded by the Research Foundation for the State
University of New York on behalf of Stony Brook University, the largest academic user of Laboratory
facilities, and Battelle, a nonprofit applied science and technology organization.